The present invention relates to a method and a device for producing fullerenes and more particularly to a method and a device for producing fullerenes capable of producing a large amount of fullerenes, particularly, carbon nanotubes with high yield.
A carbon nanotube is an allotrope of carbon and is generally known to exist in a single-walled or a multi-walled form composed of laminating rolled-up graphite sheet in a cylindrical form with the thickness of several atomic layer. The carbon nanotube is a microscopic material whose diameter ranges from about 0.5 nm to about 10 nm and whose length is about several mm.
The carbon nanotube attracts public attention as a material to be applied to many directions such as a semiconductor super-integrated circuit, a fibrous material, a hydrogen absorbing material, a catalyst, etc. as well as a cold cathode which has been already put to practical use. In particular, the carbon nanotube attracts public attention as a new carbon material, because it has a theoretically peculiar electrical property, has a large surface area although it is very fine, has a large aspect ratio, has a unique hollow configuration and has a unique surface property derived from the unique configuration.
From the above described actual circumstances, it has been desired to develop a method for easily producing a large amount of carbon nanotubes with high yield.
Fullerene as an allotrope of carbon has been also expected to be applied to a photosensitive member, a photoelectric transfer element, a solar battery, an optical limiter, toner, a non-linear optical element, a switching element, a superconductor, a transistor, a Josephson device, a sensor, a diode, a catalyst, an emitter, or the like. It has been desired to develop a method for readily producing a large amount of fullcrene with high yield similarly to the carbon nanotube.
A method for producing a carbon nanotube, wherein a mixture obtained by mixing catalyst metals, such as carbon and cobalt, is irradiated with a laser beam in an atmosphere of inert gas under reduced pressure to evaporate carbon and synthesize a nanotube and recover the carbon nanotube on, for instance, a cooled recovery rod whose end is tapered. A method wherein a carbon rod is used as an electrode and an arc discharge is generated in an atmosphere of inert gas under reduced pressure to allow a carbon nanotube to grow on the carbon rod, is known, as disclosed in, for instance, Japanese-Patent Application Laid-open No. hei. 6-280116 and Japanese Patent Application Laid-Open No. hei. 6-157016. As for the fullerene, a similar producing method has been proposed.
In the method that the mixture obtained by mixing the catalyst metals, such as carbon and cobalt, is irradiated with the laser beam, a laser light source is required, so that a device is large-scaled. In the method that the arc discharge is generated, since the carbon rod itself, which is the electrode, serves as a material for the carbon nanotube or fullerene, the amount of carbon nanotube or fullerene which can be produced is inconveniently restricted depending on the size of the carbon rod used as the electrode.